Photographic developers



Patented ec. l3. 1938 NITED STATES PATENT OFFICE I Pnoroomrmc pnvn oraas Drawing. Application August 18, 1936, Se-

rial No. 96,598. In Germany August 31, 1935 Claims. (Cl. 955-88) Our present invention relates to photographic developers. One of. its objects is to provide a new photographic developer. Another object is to provide a new photographic developer which 5 is particularly suited for fine grain development. Further objects will be seen from the detailed specification following hereafter.

Among substances hitherto known for the development of the latent image produced by exposure to light in sensitive silver halide layers by reduction of silver halide to silver, the chief are isocyclic compounds or their derivatives substituted in 1:2- or 1:4-position by aminoor hydroxyl-groups. These compounds are rapid developers. A pronounced fine-grain develop- 'ment cannot be obtained with them except in the case of para-phenylenediamine which, however, on account of its very low durability and its injurious efiect on the skin, has only little practical importance.

The present invention is based on the observation that pyrimidineswhich are substituted in 2:5-position by aminoor, hydroxy-groups and derivatives of these pyrimidines are valuable developing agents with which very good fine-grain development may be obtained.

The bodies concerned may be represented by the general formula:

r-cf tc-x x {\6 1 i;/ in which X is an amino-group or an alkylticular importance since these compounds yield a particularly fine-grain development. The compounds are capable of forming salts by the addition of an acid, for instance sulfuric acid 5 or hydrochloric acid. In the case of compounds amino-groups, or hydroxy-groups are of parwhich are sparingly soluble and contain an hydroxv-group the compounds may be converted into the bisulfite compounds; for instance 6-hydroxy-2.4.5-triaminopyrimidine is converted pyrimidine developers in the developing solution or these developers may be used with one or more of the known developing agents such as mono-methyl-paraminophenolsulfate, hydroquinone or para-phenylenediamine.

The pyrimidine developing agents may also be incorporated with or without potassium bromide and other salts in gelatin or similar material in manner itself known for providing back layers or under layers for photographic plates, films or papers,-or.the developer may be incorporated with the photographic layer itself or the support (for instance paper); in either case the exposed material may be developed directly in a bath containing only sodium carbonate, potassiuin carbonate or caustic alkali with or without addition of sodium sulfite and/or potassium bromide or other salt.

. The pyrimidine developers may be used for developing silver halide emulsion layers of any kind on film, plate, paper or the like. They are applicable forall photographic proceseses in which developers are required. The developed image is fixed in the usual manner.-

..The following examples illustrate the invention:

Example 1.--For developing films, plates or papers, there is used a solution of the following composition:

Water l 5 or- 1000 4:5 7 diamino-2:6-dihydroxy-pyrfinidinesulfate "Jgrams" 12 Potassium carbonate grams 80 Potassium bromide gram 0.2

.Sodium sulfite grams Example 2.Instead of 4:5 diamino-2:6 dihydroxypyrimidine-sulfate used in Example 1,

there is here used 6-hydroxy-2:4:5-triaminopyrimidinesulfate.

Example 3.Instead of the developing agent prescribed in Example 1, there is used in the same solution 8 grams of 2:4:5:6-tetraamino pyrimidinesulphate.

Example 4.As a back layer for a photographic film there is cast on the latter a gelatine solution of 6 per cent strength containing 2 per cent of 6-hydroxy-2:4:5 triaminopyrimidine-sulfate.

After exposure the film can be developed in a -potassium carbonate solution of 8 per cent strength. 4

Example 5.A developing solution is prepared from the following constituents:

Mono methyl paraminophenol- Example 6.--Instead of 4.5-diamino-2.6-dihydroxypyrimidine sulfate used in Example 1, there is here used isodialuric acid. I

Egcample 7.Instead of 4.5-diamino-2.6- dihydroxypyrimidine sulfate there is used 5-monomethylamino-2.4.6-trihydroxypyrimidine-sultate.

What we claim is:

1. A photographic developer comprising a pyrimidine substituted in the 2.5-positions by a group selected from the group consisting of amino-groups, alkylamino-groups and hydroz'rygroups and an alkaline reacting substance.

2. A photographic developer comprising a pyrimidine substituted in the 2,4,5 and 6. positions by a'group selected from the group consisting of amino-groups, alkylamino-groups and hydroxy groups and an alkaline reacting substance.

3. A photographic developer comprising 6-1137- dreary-2.fi-triaminopyrimidine sulfate and an alkaline reacting substance.

4. A photographic developer comprising 2.4.5.6- tetraaminopyrimidine sulfate and an alkaline reacting substance.

5. A photographic developer comprising 5- monomethylamino-2.4.6-trihydroxy-7-pyrimidine sulfate.

6. A process of developing a photographic silver halide emulsion in an aqueous solution containing a pyrimidine substituted in the 2.5-positions by a group selected from the group consisting of amino-groups, alkylamino groups and hydroxy-groups and an alkaline reacting substance.

7. A process of developing a photographic silver halide emulsion in an aqueous solution containing a pyrimidine substituted in the 2,4,5 and 6 positions by a group selected from the group consisting of amino-groups, alkylamino-groups and hydroxy-groups and an alkaline reacting substance.

8. A process of developing a photographic silver halide emulsion in an aqueous solution containing 6-hydroxy-2.4.5-triaminopyrimidine sulfate and an alkaline reacting substance.

9. A process of developing aphotographic silver halide emulsion in an aqueous solution containing 2.4.5.G-tetraaniinopyrimidine sulfate and an alkaline reacting substance.

10. A process of developing a photographic silver halide emulsion in an aqueous solution containing 5 monomethylamino- 2.4.6 trihydroxypyrimidine sulfate and an alkaline reacting substance.

GUSTAV WILMANNS. HANS FRICKE. EMIL JOACHIM BIRR. 

